The H.Pylori treatment consists of a large dose of Antibiotics.
When I went through this same treatment myself I developed (Oral Thrush) it is a side effect of this treatment.
Not everyone gets this and the symptoms are sore gums sometimes accompanid by white spots.
"Nystatin Oral Solution) is the common treatment for this and your Dr can prescribe this for you.
After your treatment remember to take a course of Probiotics to replace any good bacteria destroyed by the Antibiotics which kill of the bad.
I wish you well,